Test card for assay and method of manufacturing same
Inventors
Revilla, Ryan Alan • Heltsley, Roy James • Lee, Steve Hoe • Patel, Tej Rushikesh
Assignees
Publication Number
US-11413621-B2
Publication Date
2022-08-16
Expiration Date
2036-06-17
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Abstract
A disposable test card configured to accept a fluid sample for an assay, and a method of manufacturing same, is disclosed herein. In a general example embodiment, a test card for analysing a fluid sample includes a first substrate layer including an inlet port and an outlet port, a channel layer bonded to the first substrate layer, the channel layer including a microchannel placing the inlet port in fluid communication with the outlet port, and a second substrate layer bonded to the channel layer, the second substrate layer having electrodes printed adjacent to a target zone of the microchannel of the channel layer, wherein the electrodes are configured to raise the temperature of the fluid sample within the target zone of the microchannel when a current is applied thereto.
Core Innovation
The invention relates to a disposable test card designed to accept a fluid sample for use in assays, particularly suited for nucleic acid amplification such as PCR, offering a low-cost microfluidic platform for rapid, high sensitivity, and specificity diagnostics. The test card includes layered polymer substrates forming inlet and outlet ports, microchannels fluidly connecting these ports, and printed electrodes adjacent to a target zone to heat the fluid sample within the microchannel, thereby facilitating reactions such as PCR.
The test card construction involves multiple bonded transparent polymer layers including a first substrate with inlet and outlet ports, a channel layer containing the microchannel, additional substrate layers forming features such as mixing chambers, and a printed circuit layer with conductive and dielectric inks printed on the bottom surface. This assembly allows for fluid mixing, flow control via vacuum at the outlet, fluid detection through capacitive sensors, and localized heating within a thin analysis zone to enable efficient PCR cycling and optical analysis.
The problem addressed is the limitation of current point-of-care diagnostic assays that either lack the specificity and sensitivity of nucleic acid amplification tests or require complex equipment and processes for sample preparation. This invention solves the need for a low-complexity, disposable test card that enables early stage infection detection with high sensitivity and specificity using nucleic acid amplification under minimal-resource conditions and with minimal user training.
Claims Coverage
The patent includes three independent claims covering different but related aspects of the test card for fluid sample analysis, focusing on structural layers, fluid communication via microchannels, and printed electrode functionality.
Layered test card structure with fluid accumulation feature
A first substrate layer including an inlet port, outlet port connectable to vacuum, capture port, and an aperture aligned between inlet and capture port; a channel layer bonded to the first substrate containing a microchannel connecting inlet to outlet via a target zone and a capture port aperture aligned with capture port; the capture port and its aperture configured to accumulate fluid to prevent reaching outlet and vacuum source.
Electrodes for localized heating adjacent to target zone
A second substrate layer bonded to the channel layer having electrodes printed adjacent to the target zone of the microchannel, the electrodes configured to raise the fluid sample temperature when current is applied for causing a reaction (e.g., PCR) within the target zone.
Mixing chamber geometry and ledge for improved fluid mixing and bubble control
The channel layer includes a mixing chamber fluidly coupled to the microchannel below the inlet port, with at least a portion having a wider diameter than the microchannel to enhance mixing. The mixing chamber is defined in part by a ledge of the inlet port at the first substrate layer’s interface to the channel layer.
Test card with at least one substrate having apertures and printed circuit
A test card comprising at least one substrate with inlet, outlet, capture, and analysis apertures aligning with the target zone and a circuit printed on the bottom surface, including electrodes adjacent to the microchannel target zone to provide heating to cause a reaction when current is applied.
Surfactant coating within microchannel
The fluid microchannel includes a layer of surfactant to modify wettability and prevent bubble formation during fluid flow and elevated temperature exposure.
Circuit layering with conductive and dielectric inks
The circuit includes a layer of conductive ink printed between the bottom surface of the substrate and an overlying layer of dielectric ink to encapsulate electrical components.
The independent claims collectively cover the test card's layered polymer structure with fluid ports and microchannels, the integration of electrodes for heating within the microchannel target zone, features for fluid mixing and bubble control, use of surfactants to modify microchannel surface properties, and the printed circuit configuration including conductive and dielectric inks to enable controlled reactions and fluid detection.
Stated Advantages
Enables rapid, high sensitivity and specificity nucleic acid amplification diagnostics at point-of-care with low complexity.
Designed to use low volume fluid samples (about 10 μL), reducing reagent costs.
Layered structure allows for easily manufactured, disposable test cards with integrated heating and sensing.
Mixing chamber geometry improves fluid mixing and controls bubble formation to enhance assay reliability.
Thin analysis port zone reduces thermal mass enabling rapid heating and cooling, allowing PCR ramp rates up to 30 °C per second.
Surfactant layer inside microchannel improves wettability, facilitating smooth fluid flow and reducing bubble formation.
Documented Applications
Point-of-care nucleic acid amplification tests (e.g., PCR) for early-stage infectious disease detection.
Assays using small fluid samples such as whole blood from finger sticks, serum, urine, saliva, and tears.
Fluid analysis and detection in low-resource settings with minimal user training.
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